The invention relates to an electronic power device, and more particularly to a device comprising power chips fixed on support plates, the plates being cooled by a cooling fluid. The electronic power device of invention is particularly applicable to electronic devices used in converter type circuits for distributing power in railway applications, in which the delivered current and voltage values are particularly large.
In conventional manner, it is known to cool an electronic power component by coupling it to a heat exchanger and by inserting a ceramic plate between these two components to isolate the heat exchanger electrically from the component. Thus, document FR 2 775 416 discloses an electronic power device having power chips fixed on one face of a support plate, the other face of the plate having a heat exchanger. It is also known from that document to associate support plates in pairs by placing them on opposite sides of a cooling circuit, the heat exchangers then been disposed facing each other.
Nevertheless, such an electronic power device suffers from the drawback of generating parasitic switch loops of high inductance and thus of generating high voltage surges on switching, thus requiring the power components to be over-dimensioned so as to enable them to withstand such surges. Naturally, such over-dimensioning of power components presents the drawback of increasing manufacturing cost and of causing the power components to be larger in size.
The object of the present invention is to propose an electronic power circuit enabling the above-mentioned drawbacks of a prior art to be mitigated.
To this end, the invention provides an electronic power device comprising support plates each having one face receiving one or more power components and an opposite face in contact with a cooling fluid for cooling said power components by conduction, wherein at least one support plate is associated with another support plate disposed facing it and provided with similar power components, and wherein the power components of the two facing support plates are disposed facing one another and in the immediate vicinity of one another.
In particular embodiments, the electronic power device can comprise one or more of the following characteristics taken in isolation or in any technically feasible combination:
each support plate is associated with another support plate disposed facing it and provided with similar power components, the power components of the facing support plates being disposed facing one another and in the immediate vicinity of one another;
said support plates are distributed over two frames made of electrically insulating material, each of the frames having openings whose outlines form seats for receiving said support plates, said two frames being of a form enabling the two frames to be associated one against the other with the support plates of the two facing frames, the free faces of the two adjacent frames supporting respective cooling boxes each having a cooling fluid circulation volume and means for supplying and for removing said fluid;
said two frames are identical;
each support plate is fed with electricity via at least one emitter and at least one collector projecting respectively from two opposite edges of said support plate so that the emitter feeding one support plate is disposed on the same side as and close to the collector feeding the facing support plate;
said frames support said emitters, said collectors, and a control circuit for controlling the power components;
each of said support plates receives two IGBT components presenting a common emitter disposed between the two IGBT components and projecting laterally from one side of the frame, each of said IGBT components having an independent collector projecting laterally from the other side of the frame;
a strip of heat conducting material such as copper or aluminum is brazed or soldered to those faces of the support plates which come into contact with the cooling fluid, said strip having folds constituting micro-channels encouraging heat exchange with said fluid;
said frames and boxes are molded out of a plastics material and are assembled to one another by adhesive or by means of a sealing gasket; and
said support plates are made by assembling an electrically insulating material that conducts heat such as aluminum nitride with a composite material that conducts heat and has a coefficient of expansion matching that of the electrically insulating material such as a composite of aluminum and silicon carbide, said electrically insulating material supporting the power components and said composite being in contact with the cooling fluid.